diff options
Diffstat (limited to 'arch/x86/kernel/head32.c')
| -rw-r--r-- | arch/x86/kernel/head32.c | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c index f16c55bfc090..e5fb436a6548 100644 --- a/arch/x86/kernel/head32.c +++ b/arch/x86/kernel/head32.c @@ -49,3 +49,65 @@ asmlinkage __visible void __init i386_start_kernel(void) start_kernel(); } + +/* + * Initialize page tables. This creates a PDE and a set of page + * tables, which are located immediately beyond __brk_base. The variable + * _brk_end is set up to point to the first "safe" location. + * Mappings are created both at virtual address 0 (identity mapping) + * and PAGE_OFFSET for up to _end. + * + * In PAE mode initial_page_table is statically defined to contain + * enough entries to cover the VMSPLIT option (that is the top 1, 2 or 3 + * entries). The identity mapping is handled by pointing two PGD entries + * to the first kernel PMD. Note the upper half of each PMD or PTE are + * always zero at this stage. + */ +void __init mk_early_pgtbl_32(void) +{ +#ifdef __pa +#undef __pa +#endif +#define __pa(x) ((unsigned long)(x) - PAGE_OFFSET) + pte_t pte, *ptep; + int i; + unsigned long *ptr; + /* Enough space to fit pagetables for the low memory linear map */ + const unsigned long limit = __pa(_end) + + (PAGE_TABLE_SIZE(LOWMEM_PAGES) << PAGE_SHIFT); +#ifdef CONFIG_X86_PAE + pmd_t pl2, *pl2p = (pmd_t *)__pa(initial_pg_pmd); +#define SET_PL2(pl2, val) { (pl2).pmd = (val); } +#else + pgd_t pl2, *pl2p = (pgd_t *)__pa(initial_page_table); +#define SET_PL2(pl2, val) { (pl2).pgd = (val); } +#endif + + ptep = (pte_t *)__pa(__brk_base); + pte.pte = PTE_IDENT_ATTR; + + while ((pte.pte & PTE_PFN_MASK) < limit) { + + SET_PL2(pl2, (unsigned long)ptep | PDE_IDENT_ATTR); + *pl2p = pl2; +#ifndef CONFIG_X86_PAE + /* Kernel PDE entry */ + *(pl2p + ((PAGE_OFFSET >> PGDIR_SHIFT))) = pl2; +#endif + for (i = 0; i < PTRS_PER_PTE; i++) { + *ptep = pte; + pte.pte += PAGE_SIZE; + ptep++; + } + + pl2p++; + } + + ptr = (unsigned long *)__pa(&max_pfn_mapped); + /* Can't use pte_pfn() since it's a call with CONFIG_PARAVIRT */ + *ptr = (pte.pte & PTE_PFN_MASK) >> PAGE_SHIFT; + + ptr = (unsigned long *)__pa(&_brk_end); + *ptr = (unsigned long)ptep + PAGE_OFFSET; +} + |